Fructose excess

Fructose excess

Fructose Rich Foods

Fructose is a monosaccharide that is very common in free form in fruit , honey and vegetables . Carrots , figs , plums , peppers , courgettes , bananas and apples are particularly rich in it . Many sugary drinks, soft drinks, sweets and industrial products enriched with fructose-glucose syrups are also abundant in fructose .

In addition to its free form, fructose can also be found in food associated with other sugars or fructose molecules:

  • if combined with a molecule of glucose , sucrose originates , which is the white crystalline disaccharide extracted from beets or sugar cane commonly used as ” table sugar “; specific enzymes located in the brush border provide for the digestion of sucrose, separating fructose from glucose, which are then absorbed in free form;
  • if polymerized in long chains through β-2,1 bonds it forms inulin , a component of soluble fiber NOT digestible for humans but still useful for the functioning of the intestine (thanks to the PREBIOTIC function against physiological Bifidobacteria ). Therefore, fibers are not a source of bioavailable fructose.


Functions and Metabolism

Fructose is a sugar which, at low blood concentrations, boasts a certain “independence” from insulin , the anabolic hormone indispensable for the transport of glucose , amino acids and many other molecules from the blood into the tissues ( with the exception of the nervous one and a few others ).

Insulin, blood sugar and glycemic index

Insulin secretion and metabolism can be altered by the presence of metabolic disorders such as insulin resistance and diabetes . In similar cases, pharmacological therapy, nutritional therapy and physical exercise pursue a single objective: the moderation of blood sugar and insulin levels in order to limit metabolic damage in the short, medium and long term.
To reduce blood sugar and insulin levels , it is essential:

  1. Improve body composition ( lean mass / fat mass ratio )
  2. Increase energy expenditure and insulin receptor sensitivity through exercise
  3. Limit foods that are highly glucidic and prefer foods with a low glycemic index

Fructose , due to its insulin-independent characteristic and the need to be converted into glucose before oxidation, has a low glycemic index . For this reason, in the treatment of insulin-resistant and diabetics there is often a tendency to promote the consumption of fructose over sucrose, glucose and sweeteners (considered unhealthy additives).


Excess and Health

What is still not clear to all professionals in the sector is that EXCESSING in the consumption of fructose can be harmful to human health and even more so for dysmetabolic patients.

Excess of semolic sugars

First of all, it should be emphasized that fructose is a simple carbohydrate, therefore even eliminating any other source of simple sugars, its total intake should in any case not exceed 10-12% of the total kilocalories , an amount that can be easily reached by consuming a couple of portions of fruit and a couple of vegetables , or 3 cans of soft drinks. As can be easily understood, if the consumption of fructose is integrated into a similar diet through:

  • drinks and foods added
  • granular fructose as a substitute for sucrose

excess is inevitable.
Readers might dispute a similar observation by saying:
“… if it’s not fructose, it could be sucrose or glucose … but they’re still simple carbohydrates that help raise blood sugar; after all, it wouldn’t be healthy to make frequent use and massive amount of sweeteners!”
Very true; in fact, the first dietary correction consists in restoring good eating habits through the abolition of simple sugars used as sweeteners. This measure also facilitates the reduction of the consumption of sweet drinks, desserts and coffee .


Fructose is not a totally harmless nutrient : it is true that it boasts insulin independence BUT ONLY within certain doses; by exceeding the consumption of fructose, the increase in insulin secretion is guaranteed.


It’s not all! The conversion of fructose into glucose takes place mainly in the liver; this means that as dietary fructose increases, the hepatic workload also increases, which in a dysmetabolic patient is certainly not a negligible side effect.


Furthermore, if the liver stores of glycogen are saturated, the excess of fructose is converted into fat ( triglycerides ) with a negative impact on body weight , triglyceridemia and any problems with fatty liver disease . Experimental tests on mice and humans have demonstrated the ability of fructose to increase plasma triglyceride levels more than a similar amount of glucose. Furthermore, fructose would seem to have a lower satiating power.

Scientific researches

Numerous experimental studies have been carried out recently on the consumption of fructose in diabetics and the obese , and the results are not good. For example, an experimental 1 demonstrated that:

” Excessive fructose consumption can have deleterious effects on human health ( obesity , arterial hypertension , metabolic syndrome , hypertriglyceridemia, hypercholesterolemia and renal damage). In particular, in common nephrological clinical practice, nephropathic patients are advised to follow a low-protein diet running the risk of unknowingly increasing, as compensation, the intake of carbohydrates including fructose. It is therefore advisable to instruct nephropathic patients on a low-protein diet on how to reduce the intake of this sugar “.

Another very recent experiment 2 shows that:

” a greater consumption of fructose for 10 weeks leads to significant changes in postprandial use of nutrients as well as a significant reduction in lipid oxidation ; there is also a reduction in energy expenditure at rest compared to baseline values ​​in subjects consuming beverages sweetened with fructose for 10 weeks . “

Fructose is a glycide useful for dietary therapy but ABUSE of which is absolutely not recommended, especially in the treatment of dysmetabolic, obese and nephropathic patients. In subjects suffering from irritable bowel syndrome even a slight excess of fructose can trigger problems of bloating , flatulence and abdominal pain .



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